Seismicity of the Rio Grande rift in northern New Mexico, 1973-1983
— Daniel J. Cash and Joyce J. Wolff

In the years before adequate seismograph coverage, reports of felt and damaging earthquakes in New Mexico came mostly from along the Rio Grande rift because most of the state's population was concentrated along the Rio Grande River, which lies within the rift. Even though the seismograph coverage is now fairly substantial and the population more widely spread, the picture is little changed. The Rio Grande rift and related structures continue to be the sites of most earthquakes, although earthquakes are occasionally felt in almost all areas of New Mexico.

The Los Alamos Seismograph Network (LASN) was begun in late 1973. Current LASN station locations are shown in Figure 1. Tectonic research on the Rio Grande rift was the principal reason for establishing the network. Continuous data of good quality have been acquired for about a decade; close to 2,000 earthquakes and microearthquakes have been recorded, analyzed, and cataloged. The largest event occurred in 1976, 60 km east—northeast of Gallup, and had a magnitude M_L=. 4.6 (m_b -= 5.2).